Implement systemd journal-style multiline logging for s6-overlay.

Dockerfile.s6-overlay

@@ -89,6 +89,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 		procmail \
 		python3 \
 		python3-dev \
+		rsyslog \
 		strace \
 		vim \
 		wget \
@@ -102,6 +103,8 @@ RUN sed -i "s/rlimit-nproc=3//" /etc/avahi/avahi-daemon.conf
 COPY src/htoprc /root/.config/htop/
 COPY src/mdns.allow /etc/mdns.allow
 COPY src/nsswitch.conf /etc/nsswitch.conf
+COPY src/rsyslog.conf /etc/rsyslog.conf
+COPY src/rsyslog.d/ /etc/rsyslog.d/
 
 # Directory where rendered environment files are stored
 RUN mkdir /balena

src/rsyslog.conf

@@ -0,0 +1,34 @@
+
+global(
+    workDirectory="/var/spool/rsyslog"
+)
+
+# Load the input modules for system and kernel logging.
+# module(load="imuxsock")  # Local system logs (e.g., from journald)
+# module(load="imklog")    # Kernel log capture
+
+module(load="imfile"
+    readTimeout="500" # Sets the multi-line read timeout in seconds
+)
+
+# Custom template for 'noTimestampFormat' format
+template(name="noTimestampFormat" type="string"
+    string="%syslogtag%%msg:::sp-if-no-1st-sp%%msg:::drop-last-lf%\n"
+)
+
+# Extract service name and PID from filename pattern: {service}.log.{pid}
+set $!service = re_extract($!metadata!filename, ".*/([^/]+)\\.log\\.([0-9]+)", 0, 1, "system");
+set $!pid = re_extract($!metadata!filename, ".*/([^/]+)\\.log\\.([0-9]+)", 0, 2, "0");
+
+# Format with both service and PID info
+template(name="ServiceWithPID" type="string"
+    string="%$!service%[%$!pid%]:%msg:::sp-if-no-1st-sp%%msg:::drop-last-lf%\n")
+
+# Output all messages to stdout
+action(type="omfile"
+    file="/dev/stdout"
+    template="ServiceWithPID"
+)
+
+# Include any additional configuration files
+include(file="/etc/rsyslog.d/*.conf")

src/rsyslog.d/avahi-daemon.conf

@@ -0,0 +1,6 @@
+
+input(type="imfile"
+    File="/run/avahi-daemon.log.*"
+    Tag=""
+    readMode="2" # indented (lines starting with a space or tab belong to the previous message)
+)

src/rsyslog.d/dbus.conf

@@ -0,0 +1,6 @@
+
+input(type="imfile"
+    File="/run/dbus.log.*"
+    Tag=""
+    readMode="2" # indented (lines starting with a space or tab belong to the previous message)
+)

src/s6-overlay/s6-rc.d/avahi-daemon/run

@@ -5,8 +5,8 @@
 
 set -euo pipefail
 
-# Redirect all future stdout/stderr to s6-log
-exec > >(exec s6-log -b p"avahi-daemon[$$]:" 1 || true) 2>&1
+# This will be picked up by rsyslog and output to stdout
+exec > "/run/avahi-daemon.log.$$" 2>&1
 
 # Wait for dbus
 count=0

src/s6-overlay/s6-rc.d/certs-watch/run

@@ -5,8 +5,7 @@
 # Watch /certs directory for changes and restart confd service when detected
 # Uses inotifywait to monitor for modifications in the /certs directory
 
-# Redirect all future stdout/stderr to s6-log
-exec > >(exec s6-log -b p"certs-watch[$$]:" 1 || true) 2>&1
+exec 2>&1
 
 # Create /certs directory if it doesn't exist
 mkdir -p /certs

src/s6-overlay/s6-rc.d/dbus/run

@@ -2,8 +2,8 @@
 
 set -euo pipefail
 
-# Redirect all future stdout/stderr to s6-log
-exec > >(exec s6-log -b p"dbus[$$]:" 1 || true) 2>&1
+# This will be picked up by rsyslog and output to stdout
+exec > "/run/dbus.log.$$" 2>&1
 
 mkdir -p /run/dbus
 

src/s6-overlay/s6-rc.d/rsyslog/run

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+exec 2>&1
+
+exec rsyslogd -n -f /etc/rsyslog.conf

src/s6-overlay/s6-rc.d/rsyslog/type

@@ -0,0 +1 @@
+longrun

src/s6-overlay/scripts/confd-up.sh

@@ -1,8 +1,7 @@
 #!/command/with-contenv bash
 # shellcheck shell=bash
 
-# Redirect all future stdout/stderr to s6-log
-exec > >(exec s6-log -b p"confd[$$]:" 1 || true) 2>&1
+exec 2>&1
 
 # Populate /etc/docker.env with all container environment variables
 for var in $(compgen -e); do